Legality of the raid

The UN Charter on the Law of the Sea says only if a vessel is suspected to be transporting weapons, or weapons of mass destruction, can it be boarded in international waters. Otherwise the permission of the ship's flag carrying nation must be sought. The charter allows for naval blockades, but the effect of the blockade on civilians must be proportionate to the effect on the military element for the blockade to be legally enforceable. A ship trying to breach a blockade can be boarded and force may be used to stop it as long as it is "necessary and proportionate". The Israeli Defense Forces say soldiers acted in self-defence. An investigation, either by the UN or by the ship's flag-carrier Turkey, is required to find if the use of force was proportionate to a claim of self defence